Unit Conversions
The highest-intent, lowest-ambiguity tools on the site — everyday, engineering and universal unit conversion.
Conversion with no ambiguity: a number in, a number out. Length, weight, volume, temperature, area, speed and time in the everyday set; pressure, energy, torque, flow rate, density, viscosity, hardness, illuminance and radiation dose in the engineering set.
The universal converters handle multi-unit conversion in a single tool where you want to move between several systems at once.
This hub is kept standalone on purpose. Conversion is the clearest search intent on the site and merging it into a broader maths hub would bury it.
32 calculators in 3 sections.
Matches are ranked by relevance. Use CtrlK anytime to search the full site.
Everyday Conversions
Length, weight, volume, temperature, area, speed and cooking measures.
Temperature Converter
Convert between Fahrenheit, Celsius, and Kelvin temperature scales instantly.
Length Converter
Convert between all length and distance units — inches, feet, yards, miles, millimeters, centimeters, meters, kilometers.
Weight Converter
Convert between weight and mass units — ounces, pounds, stone, kilograms, grams, and tons.
Speed Converter
Convert between mph, km/h, m/s, knots, and feet per second instantly.
Data Storage Converter
Convert between bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes.
Volume Converter
Convert between liters, gallons, cups, fluid ounces, tablespoons, teaspoons, cubic meters, and more.
Area Converter
Convert between square feet, square meters, acres, hectares, square miles, and more area units.
Energy Converter
Convert between joules, calories, kilowatt-hours, BTU, electron volts, and other energy units.
Pressure Converter
Convert between PSI, bar, atmospheres, Pascals, mmHg, and other pressure units.
Universal Unit Converter
Convert between all common units: length, weight, temperature, volume, area, speed, energy, pressure.
Roman Numeral Converter
Convert between Arabic numbers (1-3999) and Roman numerals. Instantly translate numbers to Roman numeral notation and vice versa.
Shoe Size Converter
Convert shoe sizes between US, UK, EU, and CM (centimeters). Includes conversions for men's, women's, and kids' shoe sizes.
Engineering Conversions
Torque, flow, density, viscosity, hardness, illuminance and radiation dose.
Torque Converter
Convert newton-meters, foot-pounds, inch-pounds, and kilogram-force centimeters.
Flow Rate Converter
Convert GPM, liters per minute, CFM, and cubic meters per hour.
Density Converter
Convert kg/m³, lb/ft³, g/cm³, and specific gravity relative to water (1000 kg/m³).
Viscosity Converter
Dynamic viscosity: cP, cSt (needs fluid density), approximate Saybolt Universal seconds, and rough Engler degrees. Correlations are approximate.
Hardness Converter
Approximate steel correlations among Vickers, Brinell, Rockwell C, and a rough Shore D scale (not for acceptance testing).
Illuminance Converter
Lux, foot-candles, and luminous flux from lux × area (or lumens ÷ area).
Radiation Dose Converter
Gray, sievert, rad, and rem with Q=1 (x-rays/gamma); not for mixed radiation fields.
Magnetic Field Converter
Tesla, gauss, and magnetic field strength A/m (μ₀ relationship in vacuum).
Thermal Conductivity Converter
SI, imperial BTU·in/(hr·ft²·°F) basis per foot thickness as BTU/(hr·ft·°F), and caloric units.
Concentration Converter
ppm, ppb, mg/L, and mass percent for dilute aqueous solutions (ρ ≈ 1 kg/L).
Universal Converters
Multi-unit conversion across mass, length, energy, pressure and power.
Universal Mass Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Length Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Time Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Energy Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Pressure Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Temperature Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Speed Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Volume Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Area Converter
Convert across many related units. Enter your value and which unit it uses.
Universal Power Converter
Convert across many related units. Enter your value and which unit it uses.